In some wireless communications systems, the implementation is such that a global timing signal is not used for synchronization. A global timing signal may not be available throughout the system or devices may not be implemented to receive and recover a global timing signal. For example, the devices may have limited capability and be low cost wireless communications devices without an embedded GPS receiver. In some wireless communications systems, there may exist several groups of wireless communications devices, with different groups operating using their own notion of time. The groups may have been formed independently from one another and may be initially geographically separated from one another. For example, two groups of users may be separated from one another, with devices in a first group initially being unable to communicate to devices in a second group due to path loss considerations and the lack of a backhaul link connection between the groups. Devices in the same group may be synchronized with each other.
At least some of the wireless communications devices in the system may be mobile devices. As devices move and wireless communications devices from different groups come in closer proximity to one another and/or channel conditions change, boundaries between the groups may begin to change. Direct communications between devices of different groups may become feasible. However, devices from different groups may have to synchronize to communicate.
When a mobile device, which could otherwise be in a sleep mode, has to search for devices from other groups, with which it is not synchronized, it expends valuable battery power. In addition, a device searching for devices of other groups may be suspending at least some operations in its own group during the time it devotes to searching. If each wireless device in a group acts independently, performing its own independent search, and re-synchronizing to other groups based only on its own search results, the amount of time and resources, e.g., battery power expended and air link resources, used to fully synchronize one group to another group may be substantial.
Based on the above discussion it should be appreciated that there is a need for improved methods and/or apparatus to support synchronization between groups of devices, where the groups are not synchronized. It would be beneficial if such methods and apparatus facilitated propagation of synchronization information to members of a group and/or allowed for rapid synchronization of a group.